The present invention relates to an airbag device for protecting an occupant in the event of, for example, a vehicle collision. In particular, the present invention relates to an airbag device having an airbag including left and right half airbags to be inflated at front left and front right sides of the occupant, respectively.
Japanese Patent Publication (Kokai) No. 04-292239 has disclosed an airbag for protecting a vehicle occupant in the event of a vehicle collision. The airbag has a left half airbag to be inflated at a front left side of the occupant, and a right half airbag to be inflated at a front right side of the occupant. A common inflator inflates both the left half and right half airbags. In the airbag, a distal end of the left half airbag is connected to a distal end of the right half airbag with a tie panel.
The airbag is folded in a case and covered with a cover. In the event of a vehicle collision, the inflator, i.e. a gas generator, ejects gas to inflate the airbag rapidly in front of the occupant by pushing and opening the cover.
The inflator is disposed at an inside or outside of a base portion of the airbag. In an airbag device having an inflator disposed at an outside of the base portion of the airbag, the gas from the inflator is supplied into the airbag through a gas inlet disposed at the base portion side of the airbag. In an airbag device having an inflator disposed at an inside of the base portion side of the airbag, the inflator is entirely or partially disposed in the airbag. An example of the latter case includes a configuration in which a pair of slit openings is formed in the airbag, and a rod inflator passes through the slit openings, so that both ends of the inflator expose at the outside of the airbag.
In the airbag disclosed in Japanese Patent Publication (Kokai) No. 04-292239, the distal ends of the left half and right half airbags are connected with the tie panel. Therefore, when the airbag is inflated, the tie panel receives a center part of the vehicle occupant body in the lateral direction. When the left half and right half airbags are inflated, a larger amount of the gas may flow in one of the half airbags from the inflator, and then the other of the half airbags may be inflated later than the one of the half airbags. As described above, the distal ends of the left and right half airbags are connected with the tie panel. Accordingly, it is expected that when one of the half airbags is inflated faster than the other, the one of the half airbags may facilitate the other of the half airbags to be inflated by pulling the other of the half airbags through the tie panel.
As described above, however, the tie panel connects the distal ends of the left and right half airbags. Therefore, the one of the half airbags does not sufficiently pull the other of the half airbags through the tie panel until the one of the half airbags is inflated up to the distal end.
In view of the problem described above, an object of the present invention is to provide an airbag device including left and right half airbags for receiving the left and right sides of the occupant thorax, and a space between the inflated half airbags faces a center part of the occupant thorax in a horizontal direction.
Another object of the present invention is to provide an airbag, wherein the left half airbag and the right half airbag are inflated smoothly and substantially uniformly toward left and right sides from an early stage of the inflation.
Further objects and advantages of the invention will be apparent from the following description of the invention.
According to the present invention, an airbag device has an airbag in a folded state and an inflator for inflating the airbag. The inflator disposed at a base side of the airbag ejects gas to inflate the airbag such that a distal end of the airbag moves away from the base side of the airbag. The airbag includes a left half airbag to be inflated at a front left side of a vehicle occupant and a right half airbag to be inflated at the front right side of the occupant. Distal ends of the left and right half airbags are separated by a space facing the occupant when the airbag is inflated. The left and right half airbags have primary folded portions having vertically elongated folded states, which are then folded to have secondary folded portions having small vertically folded states to form a final folded state.
In the present invention, when the inflator inflates the airbag, the left and right half airbags receive the left and right sides of the occupant thorax having hard and strong ribs. The airbag receives and absorbs an impact from the occupant through the ribs. The inflated airbag has the space between the distal ends of the left and right half airbags. The space faces the occupant around breastbone in the center of the occupant thorax. Therefore, when the occupant body plunges into the airbag, the breastbone does not receive a large impact from the airbag, thereby reducing a load around the breastbone.
In the present invention, the airbag preferably has a distance of 150 to 350 mm between the distal ends of the left and right half airbags in the inflated state. With this arrangement, the left half airbag faces a left center of the occupant thorax and the right half airbag faces a right center of the occupant thorax, thereby securely receiving the occupant body around the ribs.
In the present invention, the airbag has the primary folded portions having a vertically elongated folded state, which is then folded to have the secondary folded portions in the final folded state. Therefore, in operating the inflator, the left and right half airbags are expanded vertically from a relatively early stage, and then expanded toward the occupant. Accordingly, it is possible to increase a first contact area, i.e. an area of the airbag contacting the occupant first.
According to the present invention, at least a part of the primary folded portion may have a rolled up portion. The rolled up portion of the left half airbag is rolled up clockwise, and the rolled up portion of the right half airbag is rolled up counterclockwise viewed from above. When the airbag is inflated, the left half airbag is deployed toward the left side of the occupant thorax from the front left side to wrap the left side of the occupant thorax. The right half airbag is deployed toward the right side of the occupant thorax from the front right side to wrap the right side of the occupant thorax. As a result, the airbag wraps and receives the occupant head from the front left and right sides of the occupant.
According to the present invention, the primary folded portions of the airbag may be folded into bellows. With such an arrangement, the left and right half airbags are deployed toward the front of the occupant to receive the left and right sides of the occupant thorax.
According to the present invention, the secondary folded portions may be separately formed at top and bottom halves of the primary folded portion. Accordingly, it is possible to adjust sizes of the folded portions at the top and bottom halves of the airbag. For example, when the top half of the secondary folded portion has a size larger than that of the bottom half of the secondary folded portion, the top halves of the left and right half airbags are inflated larger than the bottom halves of the left and right half airbags at the initial stage. As a result, the left and right half airbags approach the occupant with surfaces thereof facing the occupant in a vertical state, thereby increasing the first contact area.
According to the present invention, a common inflator may be provided for ejecting the gas to inflate the left and right half airbags. Accordingly, it is possible to reduce the number of the inflators and a production cost.
According to the present invention, the left and right half airbags may be connected with a connecting portion at midsections thereof in a direction that the airbag is inflated. With such an arrangement, when one of the half airbags is inflated slower than the other of the half airbags during the inflation, the other of the half airbags pulls the one of the half airbags to facilitate the inflation of the airbag. The left and right half airbags are connected with the connecting portion at the midsections thereof in the direction of the inflation. Accordingly, the other of the half airbags starts to pull the one of the half airbags when the other of the half airbags is inflated up to the midsection from a relatively initial stage of the inflation. As a result, both the left and right half airbags can be inflated smoothly and substantially uniformly from the initial stage of the inflation.
According to the present invention, the left and right half airbags may be connected with the connecting portion at the midsections thereof in the direction of the inflation. When the primary folded portions are formed, distal portions of the left and right half airbags from the connecting portion are folded in opposite directions along first fold lines on the connecting portion in a vertical direction. Base portions of the left and right half airbags from the first fold lines are folded along third fold lines between the connecting portion and the bases of the left and right half airbags such that the second fold lines move away from each other. The second fold lines between the third fold lines and the bases of the left and right half airbags are overlapped with the first fold lines. The distal portions from the second fold lines are overlapped with each other and rolled up. The base portions from the second fold lines are folded into bellows.
The primary folded portions have the bellows at the folded base portions from the third fold lines. When the airbag is inflated, the bellows are quickly inflated and then the rolled portions are inflated to wrap the occupant from the front left and right sides.